It is not often that the British media pays attention to Irish foreign policy decisions. It is even rarer for an Irish foreign policy decision to get more coverage in Britain than in Ireland. That is exactly what happened last week.

It is not often that the British media pays attention to Irish foreign policy decisions. It is even rarer for an Irish foreign policy decision to get more coverage in Britain than in Ireland. That is exactly what happened last week.

Last Thursday, Ireland formally became an observer member of the Organisation Internationale de la Francophonie, an organisation that is the francophone equivalent of the Commonwealth. That it was reported by British journalists, but not by Irish ones, is of a significance that I'll return to below.

What of the decision itself? Signing up to the global club of 88 members and observer members, a growing number of which are not French-speaking, was a smart move.

Ireland is one of the most internationalised countries in the world and needs to be plugged into international organisations and structures. Being at tables, making connections, articulating national perspectives in international forums and, ultimately, maximising the number of channels through which Irish interests can be pursued is vital. Small states need to be engaged in this way because they can't fall back on raw power to deliver results in a way bigger countries can. While there are some benefits of being small, there are more downsides. In a world where power is still the principle determinant in international affairs, small states must constantly work to mitigate the downsides of their relative powerlessness.

Getting involved in La Francophonie delivers on a number of objectives. First, it is a clear signal to France that Ireland is serious about strengthening the two countries' bilateral relationship. This has been a foreign policy priority for Ireland since Britain decided to leave the EU. It is well recognised that when Britain exits the EU, France and Germany will become relatively more powerful. One only has to consider how the politics of the euro-area functions to see that. Having closer relations with the EU's big two is more important than ever now that Britain is leaving.

A second benefit of participating in La Francophonie is greater access and deeper interaction with countries Ireland has not traditionally had strong ties with, notably in French-speaking Africa and south east Asia. That can be of benefit in many ways, from boosting trade to gaining votes at the UN when they are needed.

More widely still, joining such a club underscores in a concrete way Ireland's support for multilateralism as a means of managing the world. It is a core national interest of small states to prefer rules-based multilateral organisations which level the playing field with larger, more powerful states.

That brings us nicely back to Britain and Brexit. Joining the then EEC along with Britain almost half a century ago was a strategic gift for Ireland. Instead of having always to deal bilaterally with a much more powerful country, which could dictate the terms of engagement and most of the outcomes, some strands of Ireland-Britain relations were multilateralised when both countries joined. More strands were included as European integration deepened. A concrete example of the benefit of this is that since 1973 Britain has not been able to take unilateral measures against Irish traders, as it did in the 1930s and 1960s, because European law forbids it. The protection offered by the rule of European law has been a game-changer in Ireland-Britain relations.

For many reasons, Brexit is a strategic nightmare for Ireland. The nightmare continues to play out this weekend, with Brexit talks on a knife-edge. But whatever happens, Britain's departure from the most important multilateral structure that has ever existed will be bad for Ireland. The costs are already much in evidence in London-Dublin relations, Dublin-unionism relations and in Northern Ireland, where one tradition is overwhelming opposed to Brexit and the other is widely opposed to any weakening of the union that is being proposed to prevent changes to border arrangements.

Reducing these costs, preventing further damage to vital relationships and limiting the damage of Brexit will be a priority for Irish governments for years to come. With Irish and British ministers and civil servants no longer mingling on a daily basis in Brussels, alternative ways to engage with and influence Britain will need to be found.

Twelve months ago this column argued that Irish membership of the Commonwealth would be one means by which Ireland could partially fill the vacuum created by Brexit. It would also signal to unionism and the British that Ireland valued its relations with both, and that we have grown out of the outdated concerns that were once expressed about the Commonwealth club.

Shortly after that column was written, the Irish and EU side put the backstop proposal on the table in Brexit negotiations, ostensibly to ensure no change to border arrangements on this island regardless of what sort of trade deal the EU and UK work out for the long term. Whatever one thinks of it as a tactic there can be no denying that it has come with costs. It has strained relations with Britain and severely damaged relations with unionism. And on the latter relationship it is imperative to note that it is not just the DUP that is accusing Dublin and Brussels of attempting "annexation", but also the Official Unionist Party, which opposed Brexit but is also opposed to any deal that carves Northern Ireland out of the UK's customs union and/or single market.

There are no downsides to joining the Commonwealth, just as there are no downsides to signing up to observer status at La Francophonie. And just as there are multiple upsides to involvement in the French-speakers club, there are upsides to joining the Commonwealth. The only difference is that joining the latter has much bigger upsides. For Ireland to join the Commonwealth now would send a powerful signal to unionists. It would say that Ireland has collectively moved beyond vestigial hostility to Britain and the Britishness that is at the core of their identity.

While animosities among unionists towards the Irish position on Brexit have grown over the past year, so has the prospect of a united Ireland. The path to unification will be perilous. Assuaging unionist concerns about an all-island State would require the majority tradition to accept their Britishness. Joining the Commonwealth now would help demonstrate that.

Joining the Commonwealth would also send a signal to Britain, which its media would pick up even more quickly than Ireland's signing up to la francophonie. It would signal that Ireland is pursing its interests as it perceives them in Brexit negotiations, but is not doing so to take advantage of Britain in its great moment of weakness. Joining the Commonwealth would signal not only that Ireland has no animosity towards Britain, but that it values its links with the UK and wants to preserve and strengthen them even as Britain exits the EU.

It is vital that Ireland maintains the best possible relations with our nearest neighbour. This has not been easy, nor will it be easy in the future given decisions taken by the British people and the British government. It will require strategic patience and innovative thinking.

Joining the Commonwealth would improve Ireland-Britain relations and reassure unionism. If Ireland can join a French-speaking commonwealth-type club, the case for not joining the Commonwealth itself has had its last support leg removed.